Jimwell150
Active member
Is there anyone out there running a holley 350 on a 200 that can tell me or help me tuning mine. Wondering what they are running.
Anyone running a holley 350 on a 200
- Thread starter Jimwell150
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Jimwell150
Active member
My motor is stock with the dui and the holley 350. Just seem can't get it to run well. Thinking of putting the universal 1 barrel on it that classic inlines sells.
Jimwell150
Active member
I have the orange cam in and was wondering what some other people have ran for jets
65coupei6":2mu0hlbr said:
The stock DUI curve has been proven wrong for the 2-bbl 350 cfm carb on a log head engine.
And your not gonna be able to band aid a fix without having someone redo the ignition and basic carb tune
The stock 7448 350 cfm carb is prefect right out of the box for something like a 200 six with a 2V 250 or Classic Inlines engine. It has enough jetting for in excess of 150 horsepower with the power valve and main jet sizes
65coupei6 is a very humble guy, but his engine, head, cam and exhaust tune work must put out in excess of 190 flywheel hp and 220 foot pounds of torque to get the chassis dyno hp and torque figures he has quoted, which is about 223 and 144 % more oomph than a stock 200. It's one of the strongest engines here to use a 350 2-bbl carb, so it is definitely being well worked as a fuel delivery device.
With respect, as such, it bears as much relation to your application as a bicycle does to the space shuttle....
The DUI's stock settings and the over rich nature of the 7448 carb in your near stock application requires some work, and following the advise of those here is your best first port of call.
Jimwell150
Active member
Okay then what do I have to do with the ignition. I was wonder the impression is was out of the box ready for the 200.
It is, it ignites fuel and provides timing. Its probably better than the stock LoadOmatic, but not a Duraspark I, II. Money wise, it has definite advantages is that if it breaks, its easy to fix, and doesn't tie you into the unreliable aftermarket Duraspark spark amplifier unit.
With that 350 cfm carb, the DUI curve is not a perfect match, not even close. Others have been saying it for a while. With just s few hundred dollars work, the combination can work. The information here covers what to do with it. The issue is that a Duraspark has control unit costs too. The DUI has an inability to be adjusted without being sent away to a second party.
You pay you money, and make you choice.
With that 350 cfm carb, the DUI curve is not a perfect match, not even close. Others have been saying it for a while. With just s few hundred dollars work, the combination can work. The information here covers what to do with it. The issue is that a Duraspark has control unit costs too. The DUI has an inability to be adjusted without being sent away to a second party.
You pay you money, and make you choice.
Jimwell150
Active member
So I either send my dui out to get work done or what about the universal 1 barrel classic inline sells? The motor is in my rat rod. Also thinking of going back to completely stock but don't really feel like messing with points.
I think the 350 Holley is too much carb for a log head & 500 CFM is too much for a 2v head. But, people on here have run them.
Even with the DUI re-curve you still might have to play with the jets and power valve. There are way more knowledgeable people on this forum than me who have been answering your questions. So, this is just my opinion.
Even with the DUI re-curve you still might have to play with the jets and power valve. There are way more knowledgeable people on this forum than me who have been answering your questions. So, this is just my opinion.
Jimwell150
Active member
Would someone buy a duraspark II or send out the dui for a recurve in my situation?
The 7448-350 carb will work fine on your engine, drop the main jets from 61 to 59's
I install removable jets in the metering block PVCR under the power valve, but the metering block has to be modified for the addition. Yes i can do the metering block mods. I believe i normally drop the restrictions .003"-.004" to lean the WOT fuel mixture.
The DUI can be curved to your application.
I also have a reman. Duraspark already modified in the centrifugal advance & has a new vacuum advance modified to what you need. billythedistributorman@live.com
On a modified 200 the 4412-500 can be used, but needs many modifications. Bill
I install removable jets in the metering block PVCR under the power valve, but the metering block has to be modified for the addition. Yes i can do the metering block mods. I believe i normally drop the restrictions .003"-.004" to lean the WOT fuel mixture.
The DUI can be curved to your application.
I also have a reman. Duraspark already modified in the centrifugal advance & has a new vacuum advance modified to what you need. billythedistributorman@live.com
On a modified 200 the 4412-500 can be used, but needs many modifications. Bill
I know this thread is 10 years old but.... would there be any benefit to putting a plenum divider between the 2 barrels (assuming the log has been machined to accept a direct bolt-on carb)? In "simple" terms, this would cut the CFM in half to each cylinder - which may or may not be true but I had to ask!
The primary effect of splitting the intake into a dual plane is that it makes the flow in the intake unidirectional. In an open intake the air is heading one way then gets yanked back toward the carb as a cylinder on the other side inhales. If you are familiar with the effects of a dual plane vs a single plane intake on V8's- this is the same thing. The net result of dual plane intakes is improved low end torque and slightly reduced top-end power.
I'm not technical aware of 'dual plane' or other setups on the small six, though plenums can be useful. Used a 2X4 box plenum on Offy' tri-port adapter with 4412 on top built 250. Established reasonable AFR performance , consistent idle and easy tuning compared to three carbs' but wasn't any faster.
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4412 ran good on a 2Bbl adapter on mild 250 but when forced induction was added, 'modified 4412 jetting set AFR's with boost dictated the smaller 350 CFM 7448 easier to get 'in the knee' .
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from wayback machine post - ... a stock 200 with a 7448 or worse a 4412, would be doubtful upgrade
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hav fun
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4412 ran good on a 2Bbl adapter on mild 250 but when forced induction was added, 'modified 4412 jetting set AFR's with boost dictated the smaller 350 CFM 7448 easier to get 'in the knee' .
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from wayback machine post - ... a stock 200 with a 7448 or worse a 4412, would be doubtful upgrade
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hav fun
Separating #1,2,3 from #4,5,6, each with it's own barrel. Hard to do on a log for sure. Blairsville Ed did it on the stock log of a 300. Little change.
Blairesville Ed did it on a stock log 240 and there was a big change.
Yes, I should have said that too! B'ville Ed reported the split intake 300 didn't do much, the 240 it did. Good catch, thanks.
My 78 200 with a greatly enlarged intake bore along with a steel DIY carb adapter runs great with a 500 CFM (V8 rating) large base Rochester Marine type carb. This bigger carb. was a great performance increase over the previous 27O CFM small base Rochester carb. My stock 256 Enginetech cam 200 now easily winds to 5,000 in the higher gears and only drops to 4,000 when I shift. I have 6 forward gears (C4 GV OD) with 3.55 rear gears. I am happier than hell with how my 200 runs with the large base 500 CFM Rochestor marine carb,.
